1. Field of the Invention
The invention pertains to casting riser pans for defining access openings in concrete structures, and more specifically to a casting riser pan that defines an access opening through a cast concrete structure and serves as a casting mold and seat for a removable cover inserted into the casting riser pan for closing the access opening.
2. Description of the Prior Art
Components for defining access passageway openings in cast concrete structures such as septic tanks are known in the art. An example is U.S. Pat. No. 6,484,451 entitled “Stackable Riser Resistant to Soil Movement” to Gavin, the contents of which are herein incorporated by reference, which provides for a stackable riser component that may be cast into the lid of a concrete structure for forming an access opening. Gavin also discloses stacking additional risers to form an access passageway. It is desirable to provide a cover for the access opening or passageway, and to provide a seat for supporting the cover in the access passageway. Existing covers are injection-molded or cast in concrete or other heavy material. Existing covers are cast using a removable steel pan placed in a riser cast into the lid of a concrete structure, and a concrete ring is also cast into the riser to serve as a seat for the cover.
Integrated riser and pan component for casting a cover and serving as a seat for the cover are also known in the art. U.S. Patent Application Publication No. 2003/0145527 to Meyers discloses one such riser pan. The riser pan disclosed in Meyers includes a single, frustoconical wall for casting a frustoconical cover. Riser pans such as the one disclosed in Meyers are rested on a flat surface and concrete is poured into the pan component to form the cover. A plastic handle is inserted into the concrete before the cover hardens. After the cover is made, the riser pan is placed on top of a structure casting mold and the concrete cover is placed in the riser pan for weight. Then concrete is poured around the riser pan to make the concrete structure. This process requires multiple steps, which is undesirable.
Pans may deform during the casting process. A cover as described above may seat incorrectly unless the cover is correctly aligned to match the deformation. Existing pans and riser pans such as Meyers lack mechanisms for ensuring alignment of the pan and cover. Single-walled riser pans as known in the art are especially susceptible to deformation during the casting process and are subject to weight from loads stacked on the riser pan, such as stackable riser systems, or weight from street-level objects over the riser system.
Therefore a need exists for a casting riser pan that attaches to a casting mold to define an access opening in a concrete structure and allows a cover to be cast simultaneously with the concrete structure while orienting the cover to provide effective seating, and providing support to minimize deformation of the casting riser pan and to support loads placed on the riser pan.